Abstract of a lecture upon the classification and structure of the leech : delivered before the members of the Pharmaceutical Society / by H. Letheby.

Henry Letheby

Date:: [1844?]

Credit: Abstract of a lecture upon the classification and structure of the leech : delivered before the members of the Pharmaceutical Society / by H. Letheby. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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${From the PHABMACEnxicAL Journal, Vol. IV., No. VI.'] ABSTRACT OF A LECTURE UPON THB CLASSIFICATION AND STRUCTURE OF THE LEECH, SELITEBED BEFORE THE MEMBERS Oi THE PHARMACECTICAX. lOCIETT. BY H. 3LETHEB1, M.B., Late Lecturer on Comparative Anatomy and Physiology in the Medical School of the Loudon Hospital. The lecturer commenced by adverting to the position which the leech occupies in the animal kingdom, showing that it be- longed to the Annelida, the first class of the sub-kingdom Articulata or Homogangliata. This class, which includes the worms properly so called, has been divided into four orders, one of which, the Annelida suctoria, is principally composed of the family Hirudinea or leeches : they are known by their having a soft, naked, segmented body, terminated at each extremity by a prehensile sucking disc. The anterior one has the mouth in its centre, and may or may not be armed with teeth. The intestinal canal is sacculated. They have red blood, which is kept circu- lating, or rather undulating, by the pulsation of four longitudinal vessels. Their respiration is cuticular. The nervous system con- sists of a brain and ventral chain of ganglia. They have from two to ten eyes, situated upon the dorsal surface of the anterior segments. They are reproduced by ova, and the sexes are com- bined. The family may be divided into eight genera : thus. Genus 1. Clepsine, (Sav.),-Er/joMcZ/ffi s/^ec (Lam.), Glussopora (Johnson), Glossobdella (Bl.). Body composed of 76 seg- ments. Eyes 2, 4, 6, arranged in longitudinal lines. Jam reduced to three folds, without teeth.$